Paramagnetic Resonance Study of Liquids during Photolysis. V. Acid Amides and an Imide

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Abstract
Paramagnetic resonance spectra of free radicals formed by abstracting hydrogen from simple and N-methyl substituted formamides and acetamides and from succinimide have been studied. The hydrogen abstraction was brought about by ultraviolet irradiation of a solution of the amide containing either hydrogen peroxide or acetone. Deuterium substitution showed that the hydrogen bonded to carbon is abstracted from formamide resulting in a ``non-π'' radical. A methyl hydrogen is abstracted from N-methylformamide and from N,N-dimethylformamide. The former gives a single radical while the latter gives a pair of rotational isomers. These results are discussed in relation to early NMR studies. A methyl hydrogen is abstracted from acetamide. A relaxation-time measurement on acetamide indicated that linewidths are limited by the thermal relaxation time which is consistent with a number of observations for other radicals that are discussed. The hydrogen abstracted from N-methylacetamide appears to be from the N-methyl group, and a hydrogen bonded to carbon is abstracted from succinimide. Hyperfine couplings and g values are given for all of the above radicals. N,N-dimethylacetamide gives a mixture of radicals which are probably rotational isomers.